How do I replace a lost or stolen German driver’s license?
I would suggest you contact either the Strassenverkehrsamt (department of motor vehicles) or the Stadtverwaltung (municipality office) where your license was issued and they can provide proof that you had a valid German driver’s license. You may then need to go to the Rathaus (city hall) to get a replacement and it would probably be best to take your ID card/passport with you, as well as passport-sized photos and money for any possible fee.
If it was stolen, you also need to report it to the police. You may need the police report to obtain a replacement as well.
If you no longer live in Germany, you can contact the nearest German embassy for assistance.